Ginkgo biloba leaf extract is one of the most popular herbal products on the market. The most researched formulations are standardized to contain > 24% flavone glycosides and >6% terpene lactones.
It is the extensive clinical research of these standardized extracts that have been associated with reducing the risk of diseases such as Alzheimer’s.
Unfortunately, a study published in the journal Phytomedicine is raising red flags about the quality of ginkgo biloba leaf extract that are on the dietary supplement market.
Using a technique known as high performance liquid chromatography (HPLC) scientists evaluated 42 commercially available ginkgo biloba leaf extracts.
These techniques allow scientists and dietary supplement manufacturers to identify if a botanical extract has been altered in an unnatural way. This process is often referred to as ‘adulterated’.
Here are the main results of the study:
- 3 out of 42 supplements (i.e. 7.1%) were found to be authentic Ginkgo biloba
- The most common adulterants were the flavonol glycoside rutin, and quercetin and kaempferol
How can Ginkgo biloba leaf extacts be adulterated?
- A phytochemical (e.g. rutin) can be ‘spiked’ or added to a low quality plant extract
- Other parts of the plant (bark, roots, stem) that are lower quality can be used instead of the leaf. (This important because the other parts of a plant have not been studied and can provide different phytochemicals.)
- During manufacturing a strong acid such as hydrochloric acid instead of ethanol could be used. (This is important because it will break apart, also known as hydrolyze, the natural flavones)
- Flavanols found in Ginkgo have been found in other species and could be used to look like Ginkgo (e.g. The fructus and flosStyphnolobium japonicum (L.) Schott species (syn: Sophora japonica , Fabaceae). If an extract is identified as having genistein, which is not found in Gingko, it is a different plant material.
Take away message: Many studies of high quality gingko biloba extract have been published suggesting health benefits. Unfortunately, this new study suggests that the products available on the market may be of low quality with 92.9% of Ginkgo biloba leaf extracts determined by the scientists of the study to not be ‘authentic’. Make sure when choosing a dietary supplement that high quality ingredients are used during the manufacturing process. Companies should provide this type of information – if they don’t, find another company.
Phytomedicine. 2016 April 15; Volume 23 (Issue 4) Pages :377-87.
His research on plant medicine has led to more than 45 publications and abstracts.This research has been presented at international meetings in the USA, France, Turkey, Peru, Israel, Austria, and Italy.
Categories: Brain, Plant Extracts, Plant Medicine, Quality Control